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Title: Delayed neutron method for measurement of fissile/fertile content of samples ranging from environmental to irradiated fuel

Conference ·
OSTI ID:6880687

A delayed-neutron assay method is described which is capable of accurately determining the /sup 235/U and /sup 238/U contents of a wide range of materials. The method consists of irradiation in the Coupled Fast Reactivity Measurement Facility (CFRMF) at the Idaho National Engineering Laboratory (INEL), one position in the thermal driver area for /sup 235/U assay, and a fast neutron flux position for /sup 238/U. After irradiation, delayed neutron counting is used to measure the uranium content of the sample. By utilizing fast and thermal neutron irradiation and counting cycles, the samples /sup 238/U and /sup 235/U contents are determined. Minimal sample preparation and handling are required to obtain accurate results. The method has been used successfully on a wide range of samples, including environmental (soil) samples, irradiated and unirradiated fuel, and debris from the Three Mile Island Unit II Reactor core. Measurement precision of up to 0.5% can be achieved; sensitivity for low level samples is 9 counts min/sup -1/ nanogram/sup -1/ for /sup 235/U and 0.02 counts min/sup -1/ nanogram/sup -1/ for /sup 238/U. The fissile and/or fertile contents of samples containing /sup 233/U, /sup 239/Pu, /sup 240/Pu, /sup 237/Np, or /sup 232/Th could be determined by the same method. Data from representative samples are presented to illustrate the usefulness of these techniques.

Research Organization:
EG and G Idaho, Inc., Idaho Falls (USA)
DOE Contract Number:
AC07-76ID01570
OSTI ID:
6880687
Report Number(s):
EGG-M-16084; CONF-840734-19; ON: DE84015543
Resource Relation:
Conference: 25. annual meeting of the Institute of Nuclear Materials Management, Columbus, OH, USA, 15 Jul 1984; Other Information: Portions are illegible in microfiche products
Country of Publication:
United States
Language:
English

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